tank fills even though stop valve is closed

[medleyjg]

Does this sound like the stop valve is bad? is there something internal in the stop valve that can be replaced (washer, etc..) to correct problem or should the enitre valve be replaced? If replacement is necessary, how is this done?
Also, stop valves for 2 other toilets in house work okay so I don't think it's a pressure issue.

[dc_homeplumber]

If you have a Fluidmaster or Korky fill valve, the replacement seal is quite easy to replace, inexpensive and readily available. (If unsure, Google "Fluidmaster 400A" and "Korky Quietfill" for pictures.) Either of these is normally an easy, suitable replacement. Detailed instructions are on the box.

If you have the type with the big plastic ball that raises as the tank fills, you'll be better off replacing it with one of those mentioned above.

[jadnashua]

The stop valve is one of three types: soldered on, screwed in, or compression fitted. Any one of them can be replaced.

A screwed in one is basically just unscrewed.

A soldered in one would need to be heated up with a torch and pulled off.

A compression one has a nut on the back part of it. Undo that nut, and then pull the valve off. If the nut is not in too bad condition, you can often reuse it, otherwise, you have to pull it and the ferrule off. They make a special tool to do that if it won't come off easily (probably won't).

Usually, the valves have a washer in them. You can usually replace it, but the seat may not be smooth and a new washer may not seal either.

A new valve is usually less than $5, so they aren't a big investment if you can replace it yourself. While you are at it, replace the hose or pipe from the valve to the toilet. The solid pipe may look better to some people, but the reinforced hoses are much easier to install. Hope this helps.

[Lancaster]

There are also solvent weld stop valves that glue onto CPVC pipe-quite popular in this area.In this case the pipe would have to be cut off at the valve.These are also more expensive,10 bucks and up.
There are also stop valves that connect to PEX tubing with crimp rings.Special tools are required to replace these.
And finally,just recently I have seen stop valves with push-on,Shark bite type fittings.These could potentially be quite popular but the higher price will be a factor in their popularity.

[dc_homeplumber]

I've got to pay closer attention. I skimmed through and completely misinterpreted the part in question. My apologies!